Art of lighting.



P. C. HEWITT.

ART OF LIGHTING.

APPLICATION FILED SEPT- 18. 1909.

1, 1 50, 1 1 8. Patented Aug. 17, 1915.

6 SHEETS-SHEET l.

WITNESSES: 2 INVENTOR 7/ I 1 BY A I QM dv/ ATTbR/MEK P. C- HEWITT.

ART OF LIGHTING.

APPUCATION FILED SEPT-18.1909- 1,150,118. Patented Aug. 17, 1915.

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ATTb/MEY il i lil {III IIIIV I IIIII @X F l l 1 5 I 5 MM M: S n N. W 9 4P. C. HEWITT.

ART OF LIGHTING.

APPLICATION FILED SEPT. 18. I909.

1,150,118, Patented Aug. 17, 1915.

6 SHEETS-SHEET 3.

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IIVVENTOR 843w aft W7,

ATTORNEY P. C. HEWITT.

ART OF LIGHTING.

APPLICATION FILED SEPT-18.1909.

1,150,,1 18. Patented Aug. 17, 1915.

6 SHEETS-SHEET 4.

I WITNESSES: IIVI/EIVTOR ATTORNEY P. C. HEWITT.

.ART OF LIGHTING.

APPLICATION FILED SEPT-18. 1909.

1,150,1 18. Patented Aug. 17, 1915.

6 SHEETS-SHEET 5- WITNESSES r/v ENfO/i ATTORNEY P. C. HEWITT.

ART OF LIGHTING.

APPLICATION FILED SEPT. 18. 1909.

1,1 50, 1 1 8. Patented Aug. 17, 191 5. N

6 SHEETS-SHEET 6.

PORCELAIN UGHT SCATTERING SURFACE.

FLUORESCENT FILM 0R COATING.

PAPER OR CALSOMINE.

LIGHT SCATTERING SURFACE FLUORESCENT FILM 0R COATING.

FLUORESCENT MATER AL WITH INTERNAL LIGHT SCATTERING SURFACE.

WITNESSES: l/VVE/VTUR l QA A I 4 TTORN Y n iTE STATES, PATENT onEIcrETER coornn HEWITT, or RINGWOOD MANOR, NEW JERSEY, AssIeNon, BY MESNEASSIGNMENTS, To COOPER HEWITT ELECTRIC COMPANY, oEnoBoKEN, NEW J'EB SEY,A CORPORATION OF NEW JERSEY.

ART OF LIGHTING.

Specification of Letters Patent.

Patented Aug. 17, 1915.

Application filed September 18, 1909. Serial No. 518,325.

To all whom it may concern Be it known that I, PETER COOPER HEW- ITT, acitizen of the United States, and resident of Ringwood Manor, county ofPassaic, State of New Jersey, have invented certain new and usefulImprovements in the Art of Lighting, of which the following is aspecification.

My invention comprises certain improvements in the art of lighting, forincreasing certain color values from a source of light, and moreparticularly to producing a means for transforming light waves from asource into light waves of a desired character, and means for.emitting'the transformed waves so as to add light of certain color valueor wave length to the light emitted from the source, supplementing it bymeans of transformed waves, so that the resultant com- J bined light hasa desired color value.

In a patent for producing colored light rays, issued-on December 22nd,1908, No. 907,598, I have described certain methods and means forobtaining a transformation of light waves of certain wave lengths intorays of other wave lengths; that is to say, converting certain rays ofone spectrum into rays yielding a different spectrum, by means offluorescence, and for mingling the resulting converted waves with thosefrom the source of light. In said prior patent, I described theinvention as applicable to cases where a source of light is deficient insome desired. portion of the spectrum, and illustrated the broad methodas applied in a case where light is deficient in a desired portion ofthe spectrum.

My present invention relates to certain improvements, both with respectto the broad subject-matter of producing different colored light bytransforming rays from any light which is deficient in some portion ofthe spectrum deemed desirable for illumination, and also with respect tothe more specific case of increasing the "red rays by transforming theenergy of light of shorter wave lengths into light of longer wavelengths in connection with any source in which either a greater amountor a greater proportion of red light is desired.

I have foundthat'economical and eiiicient light transformers can beproduced by using a material capable of promoting fluorescence andsupporting the same in a carrier in connection with means for enablingthe material to develop its fluorescent properties, and

fluorescent dyestufl, the latter can exert its fluorescent properties toa high degree, but

the use of liquids as light transformers under practical commercialconditions is attended by obvious disadvantage. On the other hand, Ihave discovered in producing light reflectors or filters by usingbinding materials to form a paint or film, these materials may notpermit the fluorescent material to exert its property of fluorescence tothe fullest extent when used alone, and that it is desirable toincorporate therewith a promoting medium which will so alter the stateof the carrier or binder as to permit the fluorescent material to fulfilits functions as a light transformer.

One of the features of my present invention consists in bringing thefluorescent material into a medium which is solid and strong enough formechanical purposes, and yet the conditions are such that fluorescentmaterial is allowed to develop its characteristic action. The latterconditions are attained by the use of a promoting material incorporatedin the carrier for the purpose of modifying its nature to bring aboutthis result.

From the above explanation, it will be seen that in order to constructan economical light transformer having mechanical properties suitablefor practical commercial use, three components become necessary: (1) Amaterial capable of promoting fluorescence; (2') a carrier or binder;and (3) a medium which added,to the carrier promotes the fluorescence ofthe material by modifying the condition of the carrier. And, further, Ihave found that a medium or means aflordinq reflector surface orsurfaces of the light difl'using or light scattering type exercises animportant function with respect to efiiciency or fluorescent materialswhen used for transforming light in assisting them to emit thetransformed rays, whether in solid or liquid solution or mixture, Thissurface cffeet ma be made effective by reason of the physica nature orform of the material or mixture itself or by reason of its relation toother material associated with it, whereby the required surface relationis created. The conditions under which the relation isattained inpractice seem to justify the theory that the impinging light rays beingtransformed and as it were re-originated in the substance of thefluorescent material are propagated at many different angles and some ofthese are angles which bring the light back to the emitting surface atangles of total internal reflection therefrom, and in the case of a filmhaving smooth parallel surfaces any such rays may be internallyreflected and re-reflected until partially or wholly dissipated. If,however, the surface or surfaces in contact with the rear of the film,or, in certain cases, the internal surfaces, are efficient reflectors ofthe non-assorbent, light scattering type, of which .the most typical isa brilliant white surface, any rays totally reflected from the exteriorsurface and returning therefrom find in their path an efficientreflector, which being light scattering will turn back the lighttowardthe emitting surface at angles, most of which will be angles ofemission. If it should happen that some portion of the light thus turnedback again strikes the emitting surface at an angle of total reflectionand returns again toward the rear, it will be again eflicientlydispersively reflected toward the emitting surface. Thus with a thinfilm of fluorescent medium practically all of the light reaches thesurface at angles of emission, after traveling through the fluorescentmedium distances which are great as compared with the thickness of thefilm. In this way the fluorescent medium is employed so as to insure theutmost efliciency both as to its transformed action and as to its lightemitting capacity. In case the fluorescent material is carried by atranslucent carrier, this effect may be produced by making the surfaceor backing on which it is held a light dispersing or a liglit scatteringreflector, as distinguished from an image reflector, the reflectingmaterial itself being relatively opaque. It inay be explained withreference to what I have termed image reflectors, thatthey include allpolished mirrors or mirror like surfaces even when made irregular, as inthe case of ordinarv corrugated or crinkled tin or tinfoil, which do notserve to produce even approximately the conditions afforded by materialof essentially light scattering structure, such as white calcimine, orporcelain or even useful approxi mations thereof. I account for this onthe theory that where the corrugations or wrinkles of the tin or tinfoilare of such size that the fluorescent coating approximately follows theshape of the tin, the situation and functioning is that of plane mirroror image reflection, that is to say, the light is either reflecteddirectly out of the fluorescent film and thus travels through theminimum thickness thereof or if reflected so as to have a longer, moreeflicient, path is totally reflected from the inner emissive surface andis lost. It may also be explained with reference to the substances ormaterials suitable for light dispersing or light scattering reflectorpurposes, that the functioning for purposes of the present inventionrequires that the material be essentially light reflecting asdistinguished from light absorbing.

Nearly all solid bodies reflect some material fraction of the lightwhich falls upon them, for otherwise they would not be visible to theeye, and such reflection is light scattering or otherwise they would notbe visible from all directions, but most of these absorb more light thanthey reflect and would never be selected for my purposes. The best testof usefulness of materials, is afforded by the eye, the substances ormaterials having the most brilliant white appearance, and usefulapproximations thereof, being indicated as desirable provided of coursethey are physi cally and chemically adapted for the purpose. In general,light absorbing surfaces and surfaces formed of substances suitable forproducing phosphorent effects would not be employed for my purposes. Inthis case the fluorescent material is associated with another surface ofsuch character as to cause light rays transformed by it to be emitted orliberated from it. In some cases the light dispersing surface may bemore intimately associated with the light transforming material bycausing the material itself to possess such surface by reason of itsphysical form or condition, or by incorporating in the carrier amaterial providing such surface. The function of light dispersion may beproduced by one composite substance instead of by a light scatteringbody separate from the fluorescent material.

As a desirable embodiment of my invention, I may employ collodion, orother cellulose compound, or gelatin or glue as a translucent carrier,and the material which I have called the promoting medium, may consistof castor oil or other suitable material in the case of collodion, andglycerin in the case of glue or gelatin. By use of such materials, thefluorescence material is caused to exhibit its fluorescent properties toa remarkable extent, while in a practically solid state.

I have devised various special forms of reflecting devices and means ofapplying the same to different forms of lamps for securing a resultantillumination pleasing to the eye. The lights produced by most, if notall artificial illuminants, are deficient in portions of the spectrumwith respect to many of the purposes for which they are used, and suchdeficiencies may be corrected by my invention. Hence, my-invention isapplicable, not only to Cooper Hewitt lamps or mercury vapor lamps, butalso to other illuminating sources, including Welsbach mantle lamps,incandescent filament lamps, such as tungsten and tantalum lamps andordinary carbon filament lamps, and'to arc lamps, and also to daylight.

In case of the mercury vapor lamp, it has long-been recognized that inview of 1ts many economical advantages, alight transformer capable ofconvertingsome of the rays emitted by this lamp into rays of longer wavelengths would be extremely useful, because it would permit the minglingtogether of the rays of various wave lengths in the proportion desiredand thereby supplementing the spectra and making possible the productiontherefrom of a light approximating ordinary daylight. In the severalother illuminants of commerce, it is often desirable to add certain raysso as to reinforce the spectrum, and in such cases my invention isapplicable and useful.

As an example, the above results may be achieved by selecting rhodaminsuch as rhodamin B or rhodamin G of commerce,

.as the flourescent mate 1 ial in constructing a light transformer inaccordance with my invention in the manner hereinafter described. Withthis dyestuff incorporated in a carrier mixed with the promoting mediumas aforementioned, it is possible to transform the rays emitted by amercury vapor lamp into other rays, so that the mixture of the raysemitted by this material with untransformed rays directly emitted fromthe lamp, will so supplement the normal spectrum that the resultantlight may be made to resemble ordinary daylight to a remarkable extent,and for some purposes may be made even more desirable. r

In preparing the active material of a light transformer in accordancewith my invention, a small quantity of fluorescent material togetherwith the promoting medium, such as castor oil is dissolved in a solutionconsisting of the carrier dissolved in a suitable solvent in suitableproportions, and I will now describe for the purpose of illustrating myinvention, two examples of the manner in which it may be carried outwith materials requiring different solvents.

Preparation of the active material for light transformer using collodionas a carrier.The fluorescent material, for instance, rhodamin B isdissolved in absolute alcohol. The color goes into solution and thesolution is then filtered to free it from other matter, such as glucoseor dextrin, sulfate of soda, etc., which may be associated with suchdyestuffs as obtained in commerce. To a solution of collodion there isadded a quan tity of castor oil varying from several per cent. up to sayeightly per cent. or more of the dried collodion solution, beyond whichthe material tends to become sticky. A suitable quantity of the solutionof rhodamin B in alcohol is then added and a film prepared, either bypouring the solution so obtained on a sheet of glass, from which it maybe stripped, or by painting on paper or -porce lain or other suitablefoundations having a light dispersing reflecting surface. The film orcoating is allowed to dry and is then ready for use ,in the mannerhereinafter described as the active material for a light transformer.Excellent results are obtained by preparing a coating as follows: To twohundred and fifty (250) grams of collodion containing five per cent.(5%.) to six per cent. (6%) of solid matter dissolved in alco hol andether, representing about twelve (12) grams of solid matter, is addedfrom five (5) to twenty (20) grams of castor oil and six-tenths of agram of a ten (10%) per cent. alcohol solution of rhodamin B; thissolution containing, therefore, six one-hundredths (6/100) of a gram ofrhodamin B. These amounts may be changed by reason of commercial orother requirements without departing from the spirit of the invention.Instead of rhodamin B, another rhodamin as rhodamin G may be employed.Care should be taken to have the collodion as free as practicable fromwater, as water tends to impair or render uneven the coatingwhenvapplied to a surface, on drying. The materials as above referredto, are mixed carefully and formed into a more or less viscous liquidfor preparing the active material of a light transformer. Two or threerapidly flowed coatings successively applied, will give good results.

As stated above, there are various ways of using this coating material;one is to coat it directly upon a reflecting surface which ispractically impervious to light waves, and at the same time not an imagereflecting surface and for this purpose the use of a mat surface hascertain practical advantages, although a very smooth light scatteringsur face appears more efficient. White paper may serve as a backing. Agood surface may be obtained by a coating of white lead, zinc white,magnesia, or French white, upon a suitable foundation,such, forinstance, as paper, pasteboard, metal or other material. The white maybe mixed with the gelatin and glycerin in convenient proportions and asuitable quantity of water added for ap plying to the foundation. I havefound, for instance, a mixture of a suitable quantity of gelatin, saythirty parts (30) with twenty parts (20) of glycerin and three hundredparts .(300) of white lead and about two hundred parts (200) of water,

serve to make a calcimine well ada ted to the purpose. The calcannne maye applied to the surface by flowing or by a brush, and when dried, theglue, gelatin or collodion mixture containing the light transformingmedium is applied in hke manner to the coated surface and allowed todry. The gelatin calcimine has the advantage of being non-absorbent forthe collodlon mixture, if the latter does not contain too much water,thereby giving a good surface contact. Care should be taken to avoid thepresence of air bubbles and to secure a smooth, even distribution of thecollodlon mixture. It will, of course, be understood that theproportions of materials employed may be variously modified withinreasonable limits, but those mentioned afford very excellent results.Instead of coating a surface with calcimine, a film may be formed, thereverse side of which may be coated with the calcimine, and the wholeattached to a support.

I have found that excellent results may be obtained where the diffusingsurface is incorporated in the light transforming material. This may beaccomplished by mixing the zinc white or opaque reflecting material withthe collodion-rhodamin mixture. The material may be made in a film andcoated on a suitable backing, if desired. lVithout attempting to explainaccurately the action which takes place, the indications are that whenthe light transforming material has image reflecting surfaceor is coateddirectly upon an image reflector surface, the transformed light rays arenot freely emitted from the light transformer; when, however, it isassociated with a lightdispersing surface as when the material is lightscattering or the surface in contact with the varnish islight-scattering, the transformedvblight waves are more freely emittedand may be readily combined with the rays from the origin. This seems tobe true when a reflecting material is mixed with the light transformer,although in the latter case, there would appear to be a some- 'lml lowerefficiency of emission probably due to the fact that a portion of thetransformer is then occupied by such material.

An example of dispersive reflection in the active material, due to itsphysical condition or form, may be had by taking the above describedcollodion castor oil-rhodamin mixture made by alcoholic solution, andrapidly mixing it with water as by a jet, in which case the materialtends to become fibrous in physical structure, and, when dry, it may befurther comminuted for use as a powder.

Preparation of the active material for a light transformer using gelatinor glue as a c1zrr2'er.When gelatin is used as a carrier, a quantity oftransparent gelatin is dissolved in water. Glycerin to the amount ofabout twenty-five per, cent. (25%) of the dry weight of gelatin is addedto the solution, together with a suitable quantity of rhodamin G,prepared as above, or' ther suitable fluorescent material. The amount ofglycerin depends on the quality of the glue or gelatin, it beingadvisable to use as much glycerin as commercial practice will permit.Rendering the gelatin iacid aszby acetic acid assists the fluorescencepromoting action. This solution is used to prepare a film or may bespread on --a surface composed of efficiently reflectinglight-scattering material as for instance white paper, porcelain, etc.The film is allowed to dry and is used as a light-transformer in themanner herein described.-

When made in accordance with the pre-' ferred method herein set forth,the'composite material constitutes a flexible solid or semi-solidelastic body, which consists of a fluorescent material, a solid carryingmaterial, and a promoting material. There is reason to believe that theassociation of the materials should be such that the fluorescentmaterial remains as if in solution and diffused through the carryingmaterial, thus aiding fluorescence in the carrying material andrendering the composite body more flexible and elastic to conditionspermitting free vibration and development of fluorescence therein.

The light transformers obtained by the above methods, are suitable fortransform-- ing certain non-red rays into rays-of yellow, orange, andred color. Other mate-= rials may be used for other colors; eosin foryellow and some reds, for instance, while uranin gives itscharacteristic color. The light transformers are supported in such aposition that a portion of the rays from the lamp impinge thereon andare transformed and reflected to the surroundings and in so doing becomemixed with the direct light emitted. It is important that the materialof the device should not become overheated beyond its active temperatureand its location with reference to the source of illumination should bedetermined with reference to the characteristics of the plate and thefilm afterward stripped off and applied to a dispersing reflectingsurface, great care should be taken to insurea perfect surface contactbetween the two surfaces and in order to obtain best results thesurfacecontact should be sharply defined and the union definite. In the case ofits use as a coating material afterthe manner of a paint or varnish, itis preferably that the dispersing surface should not be absorbent, inorder that a sharp surface contact be insured between the coating andthe surface whereby a high efliciency ,is promoted. The above referredto relations of the light scattering surface to the active materialholds irrespective of whether it is used in the form of a backing or asintermixed particles and irrespective of whether the surfaces are glossyor not. A white porcelain plate forms a very suitable background.

It will be clear from the foregoing that by means of my invention lightfrom any source may be enriched by any Wave length obtainable fromfluorescent material by the use of a suitable carrier and a lightdispersing reflecting surface associated therewith to form a reflectorafter the manner above described.

In the accompanying drawings I have shown an application of myinvention.

In the drawings Figures 1 and 1 are side and end views showing theinvention as applied to a mercury vapor lamp. Fig. 2 is an elevation ofa WVelsbach mantle light showing a reflector in section; Figs. 3, 4, 5,and (l are similar views, of various forms of filament lamps showingvarious forms of my invention applied thereto. Figs. 7, 8, and 9 areexaggerated or schematic views intended to illustrate some of thefunctional relations in various of my fluorescent reflecting devices andmaterials.

Referring to Fig. 1; 1 represents a source of light, such as the mercuryvapor lamp, and 2 represents a suitable holder for supporting the lamp.This holder also carries the frame 3, carrying a reflector 4,constructed in the manner hereinabove described. The reflector shown iscurved transversely, and in case the curvature'iapproximates an arc of acircle, its centrsof curvature is preferably remote from the axis of thelamp. For instance, in Fig. 1, the reflector being less than asemi-cylinder, its center of curvature would fall considerably below theaxis of the lamp. The shape of this cross-section may be varied withinwide limits, however, the shape being adapted generally to its distancefrom the source of light and to the space to be illuminated.

In Fig. 2, 5 represents a well known type ofWelsbach lamp and 6, areflector placed above the same, serving to transform a portion of therays emitted by the mantle and to cause them to mingle with thoseproceeding direct from the mantle. The eifect is to add very largely tothe red rays and thus render the illumination very closely like thatofsun-light. An annular ventilating lamp having a metallic 'or other'wellknown form-of filament and 8 represents a fluorescent reflectorupon-one side of the lamp, the sup ort 9 being broken away to show this.T e support 9 is'held in'place by an ordinary spring cli 10.

Fig. 4: illustrates a simi ar lamp having a more or less transparentshade 11, held' by a wire support 11", and having a relatively smalltransforming reflector 12 inserted within it for adding the requisitered ra s.

In Fig. 5, a substantially plane annu ar reflector 13 is shown as placedabove an ordinary carbon filament lamp 14. i

In .Fig. 6, the reflector 15 has the-shapeof a truncated. cone, thusacting partly as a shade or screen so that it intercepts and transformsa greater proportion of the light than does the shade of Fig. 5. Theaddin Fig. 3, 7 represents an incandescent tion of the red rays may besuch as to give a rose tinted illumination. Fig. 6' also shows thefluorescent portion 15 of the reflector,-supported a predetermineddistance away from contact with the source by means of a heat resistingportion 15, whichmay be of metal, asbestos, etc., and .0011- structedwith draft passages 17, adapted 'to permit a draft, thereby improvingthe heat insulation of the sensitive material at-15.

It will readily be seen that the adaptations of the light transformerfor various forms of illuminants, are practically unlime ited, but thoseshown will serve in general to illustrate the applications.

The active materials to be used in the above 'described and illustratedarrangements or in any other known or desired arrangement, may be any ofthe forms hereinbefore described. Illustrative examples of thefunctional relations available are illustrated in Figs. 7, 8, and 9,which, as before stated, are exaggerated or schematic views intended toillustrate the functional relations. It will be understood that in saidfigures no attempt is made to show the real appearance or portions ofparts, since this would be impossible.

As indicated by the legends thereon, Fig. 7 shows a fluorescent film orcoating applied to a light scattering surface, of which white porcelainis named as an example of a material having such surface.

In Fig. 8 the fluorescent film or coating is shown as applied to a lightscattering surface, such as paper or calciinine, which lat-' ter may beitself secured to or coated upon a more substantial support, asindicated.

In both Figs. 7 and 8, it will be understood that the exact physicaldimensions of the parts may or may not be as shown and such as resultsfrom painting the mixture upon the light scattering surface and thenpermitting it to dry, or such as results from forming a film upon glass,drying, stripping, and then applying to the light scattering surface inperfect or intimate contact therewith. Where the li ht scatteringsurface, indicated in Fig. 8, 1s calcimine, it may be applied initiallyto the front side of the support, or it may be painted upon the backside of the film before the latter is applied to the support.

Fig. 9 shows a fluorescent material with internal light scatteringsurface indicated by the dots therein. It will be understood that thethickness of the material represented by Fig. 9 may vary from that of amere varnish coat to that of a sheet of considerable thickness. Suchmaterial may be used as a separate sheet or may be used in any of therelations of the films 01' coatings shown in Figs. 7 and 8, though itwill be understood that being provided with internal light scatteringsurface, a light scatterigg background may be omitted, if desire While Ihave herein fully shown and described, and have pointed out in theappended claims certain novel features of my invention, it will beunderstood by those skilled in the art that various omissions,substitutions, and changes in the forms, proportions, sizes, and detailsof the device, of the materials used, and of their operation, may bemade without departing from my invention.

In another application filed by me July 23rd, 1910, Serial No. 573,557,claims are made to certain features described herein.

I claim as my invention:

1. A light transforming reflector consisting of a translucent materialcarrying a fluorescent material, free from light absorbent particles,and formed or provided with a reflecting surface of the white or lightscattering type.

2. A wave transforming reflector consisting of a translucent sheetcomprising trans lucent material carrying a fluorescent materialsubstantially free from light absorbent particles, and a backingconsisting of a reflector surface of the white or light scat tering typein intimate contact with the rear surface of said sheet.

3. A wave transforming reflector consisting of a translucent sheetcomprising a fluorescent material and translucent carrier therefor, anda translucent fluorescence pro- Inotingmaterial and a backing consistingof a reflector surface of the white or light scat tering type inintimate contact with the rear surface of said sheet.

1. A light transforming reflector consisting of a sheet of translucentmaterial carrying a fluorescent material, free from light absorbentparticles, and a reflecting surface of the White or light scatteringtype forming a reflecting backing and a physical support for said sheet.

5. A reflector comprising a suitable support and snow white coatingpainted thereon and a sheet of light transforming material comprising anon-rigid or flexible translucent material carrying a fluorescentmaterial.

6. A reflector comprising a suitable support and snow white coatingpainted thereon and, formed on the latter, a sheet of light transformingmaterial comprising fluorescent material, a translucent carrier thereforand a translucent fluorescence promoting material combined with thecarrier.

7. A fluorescent body comprising a sheet or film of composite material,adapted to be used in the relation of a light reflector, said compositematerial consisting of a fluorescent material, a carrier therefor, andat promoting material, said sheet being formed or provided with lightdiffusing reflecting surface.

8. A fluorescent body comprising a sheet or film of flexible compositematerial, adapted to be used in the relation of a light reflector, saidcomposite material consisting of a fluorescent material, a translucentcarrier therefor, and a promoting material, the sheets being backed by areflecting and light diffusing surface.

9. A fluorescent body comprising a sheet or film of composite material,adapted to be used in the relation of a light reflector, said compositematerial consisting of a material capable of fluorescence, a carriertherefor, and a promoting material. the front surface of said sheetbeing light transmitting and the rear surface thereof being surfacereflecting and light diffusing.

Signed at New York, in the county of New York, and State of New York,this 15th day of September, A. D. 1909.

PETER COOPER HEWITT. Witnesses:

R. A. HEWITT,

CoLEs CARPENTER.

